1. Technical Field
The present invention relates to an image forming apparatus.
2. Related Art
Conventionally, image forming apparatus such as inkjet printers that eject an ink liquid from ejection openings with respect to a recording medium to form an image on the recording medium are known.
In this type of image forming apparatus, electrical power is supplied from a drive circuit to cause piezoelectric elements, for example, to deform and generate a volume change in pressure generation chambers filled with the ink liquid, whereby ink droplets are ejected from the ejection openings that are spatially connected to those pressure generation chambers. The piezoelectric elements are capacitive because they deform in response to the electric charge amount with which they have been charged.
In this type of image forming apparatus, heat is emitted by the drive circuit when electrical power is supplied from the drive circuit to the piezoelectric elements because the ON resistance of the drive circuit and the capacitances of the piezoelectric elements form a CR series circuit.
Particularly in an elongate head where numerous ejection openings are disposed, numerous piezoelectric elements are also disposed, so the heat emission amount becomes large and a large cooling unit becomes necessary. For this reason, in image forming apparatus, even when ejector components and drive circuits can be made compact, the cooling unit cannot be made small unless the heat emission amount changes, so it has been difficult to make the head compact.
Therefore, there is proposed a technology that makes it possible to make the head compact by moving some of the heat sources to the exterior of the head to disperse heat.
However, in a drive circuit in this technology, since one electrode of each of the piezoelectric elements is used as a common electrode, when the timings of charging and discharging of the piezoelectric elements overlap, a short occurs inside the drive circuit, and therefore it is necessary to ensure that the timings of charging and discharging do not overlap.